I've been here almost 3 years now. To chime in as someone neither new or old:

1. I agree that posting links to old discussions has a chilling effect; it does for me. And it's about perception. Maybe it's all about the placement of the link, seriously. If someone responds to you with an initial, "yeah, we discussed that before," you feel shut down. But when they respond in the present, then put the link to old posts at the end of their message, it seems an optional reference, not a silencer. As I say, that's just my perception, but I don't think I'm alone.

2. Busy lives in real life: that's me, and all of us, I'm sure. Would love to have been here for all the of The Hobbit chapters, but to write up a response to a chapter discussion, it can take me up to 60 minutes to consult the books, think it through, and revise what I've written. Just don't always have the time and energy for that.

3. Yes, it's disappointing to lead a chapter discussion and only get 2 replies. No one is being shunned or ignored when they post, so I didn't take it personally when I lead a few chapters in the last LOTR discussion, but you do feel like you've started a conversation in a room full of people (a reading room, even) and awkwardly, no one replies. It's not the same as writing an informational blog--you really want to engage people actively.

Regarding chapter discussions of other Tolkien books, I recall people saying that past discussions were most robust about LOTR, and least active about The Silmarillion. The Hobbit seems to fit between those two bodies in popularity, so I'm guessing that Roverandom or any other book wouldn't attract many responses. I'm not trying to discourage the idea at all, just more of an alert that discussion leaders might not get much satisfaction from the participation level.

It seems that topical/thematic posts receive more responses than chapter discussions, or posts on very specific details. Maybe we focus on those instead to encourage participation?